Periodontitis is a common, destructive disease of the supporting structures of the teeth; a risk factor for serious systemic diseases including vascular diseases and lung diseases; and an enormous consumer of American health dollars (>$14 billion / year). However, diagnosis of periodontitis is problematic. Due to the complex nature of periodontitis, we predict that a global approach to the measurement of disease processes may be required to provide a diagnostic solution. We hypothesize that (1) The combination of tissue hemoglobin, oxygenated hemoglobin, tissue oxygenation and perfusion, tissue hydration and tissue temperature will provide a robust indicator of periodontal inflammation with site-specific diagnostic potential; and that (2) Global profiling of gingival crevicular fluid (GCF) constituents, which reflect underlying periodontal disease processes, will lead to the generation of accurate and testable diagnostic algorithms that will differentiate healthy, gingivitis, and periodontitis sites. Near Infrared Spectroscopy (NIRS) can simultaneously monitor multiple inflammatory indices non- invasively. Mid-Infrared spectroscopy (MIRS) can be used to generate molecular and sub- molecular profiles of biological fluids. Therefore, we plan to use infrared technology to obtain diagnostic fingerprints of periodontal tissues and fluids. State-of-the-art approaches to the extraction of clinically significant data from IR spectra will allow us to (A) Correlate each principle component (source of spectral variation) to key clinical data (including standard inflammatory measurements and measurements of tissue destruction); and (B) Determine the percentage accuracy of NIRS- and MIRS-algorithms in diagnosing periodontal diseases, along with the sensitivity, specificity and positive and negative predictive values. The successful completion of this research plan will pave the way for the long-term goal of delivering IRS- based technology that reliably measures periodontal tissue status and represents a simple, reproducible, reagent-free, real-time diagnostic device for the dental clinic or periodontal operatory. IR spectroscopy may also provide standardized inflammatory measurements - an invaluable, but so far elusive, research tool for periodontics. The successful development of IR-based imaging techniques can have a revolutionary effect on our approach to the diagnosis of periodontal diseases and a profound effect on the distribution of oral health expenditures. Diagnosis of periodontitis is problematic. Therefore, we hope to test the potential of infrared spectroscopy as a diagnostic tool in periodontics. The long-term goal of this research project is to deliver an IRS-based technology that reliably measures periodontal tissue status and represents a simple, reproducible, reagent-free, real-time diagnostic device for the dental clinic or periodontal operatory. [unreadable] [unreadable] [unreadable]